Mobile phones of the era complicated investigators’ task

MODERN smartphones contain a trove of personal data linked to social media accounts, internet storage services and satellite navigation apps, which have made them a vital resource for criminal investigations.

But in 2007, when Madeleine Mccann went missing from the Portuguese resort of Praia da Luz, the iphone was still a month away from going on sale. Most people carried basic mobile phones without touchscreens, internet connections and GPS chips.

However, mobile phone records, including location data and records of calls and texts made between numbers, could still be used to trace criminal suspects and potential accomplices.

Yesterday, Scotland Yard said a 30-minute phone call was made to a Portuguese phone owned by a newly-identified suspect in its investigation into Madeleine’s disappearance, just an hour before she vanished.

The key to obtaining mobile phone data in the days before internetequipped phones was the mobile operator that a phone number was registered to. Since most phones did not have Wi-fi connections, all calls and text messages would have had to travel over a mobile network.

Portugal’s three mobile networks – TMN, Vodafone and Optimus – would hold a record of every phone call and text message made and received by a number for billing purposes, including how long calls lasted, and what number was on the other end of the line.

Networks would also have been able to roughly track users’ locations, by seeing which cellular base station a phone had “pinged”.

Advanced techniques allow police to more accurately gauge a phone’s location by triangulating its signal between multiple cell towers, although this is easier in urban areas with many towers than in coastal Portugal, where coverage may have been patchy in 2007.

Location data based on cell towers is not as accurate as GPS, and has previously been thrown out of court for being unreliable. Retrieving what was said in text messages and phone calls is more difficult. Without a wire tap arranged in advance through a court or- der, networks do not tend to keep the content of messages or recordings of phone calls.

It can also be difficult to connect a phone number to an individual. While mobile phones with monthly contracts were linked to billing information and addresses, pay-as-you-go phones did not have to be registered.

Portugal introduced the world’s first pay-as-you-go phone, and it would have been easy for foreign visitors, such as the German national identified in the Madeleine Mccann investigation, to buy top-up SIM cards without ID checks.